1704. Determine if String Halves Are Alike

You are given a string s of even length. Split this string into two halves of equal lengths, and let a be the first half and b be the second half.

Two strings are alike if they have the same number of vowels ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'). Notice that s contains uppercase and lowercase letters.

Return true if a and b are alike. Otherwise, return false.

 

Example 1:

Input: s = "book"
Output: true
Explanation: a = "bo" and b = "ok". a has 1 vowel and b has 1 vowel. Therefore, they are alike.

Example 2:

Input: s = "textbook"
Output: false
Explanation: a = "text" and b = "book". a has 1 vowel whereas b has 2. Therefore, they are not alike.
Notice that the vowel o is counted twice.

Example 3:

Input: s = "MerryChristmas"
Output: false

Example 4:

Input: s = "AbCdEfGh"
Output: true

 

Constraints:

  • 2 <= s.length <= 1000
  • s.length is even.
  • s consists of uppercase and lowercase letters.

Rust Solution

struct Solution;

use std::collections::HashSet;
use std::iter::FromIterator;

impl Solution {
    fn halves_are_alike(s: String) -> bool {
        let n = s.len();
        let s: Vec<char> = s.chars().collect();
        let vowel: HashSet<char> =
            HashSet::from_iter(vec!['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U']);
        let left = s[..n / 2].iter().filter(|c| vowel.contains(c)).count();
        let right = s[n / 2..].iter().filter(|c| vowel.contains(c)).count();
        left == right
    }
}

#[test]
fn test() {
    let s = "book".to_string();
    let res = true;
    assert_eq!(Solution::halves_are_alike(s), res);
    let s = "textbook".to_string();
    let res = false;
    assert_eq!(Solution::halves_are_alike(s), res);
    let s = "MerryChristmas".to_string();
    let res = false;
    assert_eq!(Solution::halves_are_alike(s), res);
    let s = "AbCdEfGh".to_string();
    let res = true;
    assert_eq!(Solution::halves_are_alike(s), res);
}

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